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The UV-3R family of radios are dirt cheap 2W handheld transceivers with reasonably good stock features especially given the price. They can be very easily modified to take advantage of the on board MCU and crappy programming of that MCU.
The UV-3Rs are software controlled radios (not SDRs) the DSP isn't controllable beyond squelch thresholds (afaik) which means only when and where to transmit and receive not any changes to modulation or demodulation.

Quick interface to program rx freq, tx freq, power and PL code very quickly for repeaters. No offset, you just start with the rx freq and shift it by whichever amount you want. This will allow allow you to turn off the tx, or operate satellites. At any point during this mode, you can hold the mem channel and it will ask you which number you want to save this to.

Memory mode will allow you to go through your saved memory. At any point you can press menu and change more details about the channel. The details will include power with granular level, DTMF TX/RX, and other functions TBD. This mode will show the channel name and the freq underneath it.

Satellite Mode: Auto tuning of the frequency with response to the Doppler shift.

(not yet) Digital mode. Hopefully I could add some text base digital data for rx and tx. You might need to tx the text using morse code since there is no alpha numeric keypad on the radio. The digital mode will also include a store and repeat message forwarding.

(mostly implemented) Computer mode: All the functions of the radio including the RDA1846 registers, TX, and RX will be controlled through the serial port on the radio.

Fox/Hunt mode. Can be used to transmit a signal intermittently (like call sign morse code). Or send the RSSI signal into the audio, and with a directional antenna you can go hunting.

(not yet) Advance mode: Any RDA 1846 register can be set manually and saved for during startup.

(not yet) If the digital mode works, then RF programming of the radio. This will allow anyone to send you repeater information from their memory locations. I will work by selecting a memory channel to rx, and pressing a button. Then on another radio you can send the programming info.

(not yet) APRS mode: Boots straight to 144.39 mhz (or whatever you set it to), doesn't accept inputs, stays on the set frequency.

A wide based flush fit BNC (or similarly durable connector) adapter (sometimes called an antenna saver) given the short mating cycle "SMA connectors are rated for up to 500 mating cycles" citation via Wikipedia

Also you can replace the adapter much more easily than the SMA connection in the radio.

You can even apply some threadlock (the light duty stuff) to the threaded part and still keep the groundplane continuity because of the wide base on the adapter touching the rim of the SMA socket.

Get a dedicated antenna for the VHF and UHF (or whichever you will use the most). The dedicated antennas will do wonders for performance as the stock antenna is really pretty horrible and multiband antennas in general can only be so good on any given band they are tuned for before the others suffer, so they end up being okay at best on all of them. If you followed the above then get a BNC terminated antenna and don't worry about adapters for the antennas.